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Read through the forum and watched a bunch of videos... still looking for help...  RSS feed

 
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We are working on a rocket mass heater this weekend in a light straw clay house we built last summer. My friend pre-built a J-Tube which was drawing and sounding rockety before we hooked up the rest of the stuff... we then hooked up the rest of the stuff and it was working (sort of, not awesomely rocketing) but burning... We then insulated with cob mix that includes clay and sand.... its still not burning great and it is now smoking out the house. The venting tubes are resting on concrete slabs. The exhaust goes out the wall a few inches above the bottom of the J-Tube and then the pipe goes up aprox 10 ft on the outside of the building. We are trying to figure out how to get more pull and avoid the exhaust going the wrong way.


Anyone have any suggestions??
 
pollinator
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Shannon F. : Did you go to rocketstoves.com and download your PDF copy Of Ianto Evans' great book "rocket mass heaters'', $15.oo U.S.,
it will help you diagnose your problem, and be quite useful when you are 'Talking', to other Rocket builders on this site. You will have to be
prepared to give the sizes of your pipe, and size and dimensions of your feed tube, burn tunnel, and height of the heat riser, how close to
the inside of your barrel, thickness of insulation in inches on the outside of the Heat Riser, Size of your barrel and exactly how you went from
barrel to the start of your horizontal exhaust pipe, you are also going to be asked about clean outs. Lots of pictures, especially while you were
making your rocket will help tremendously ! Be Safe, keep Warm, PYRO magically Big Al
 
Shannon Freed
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Thanks Allen... will download and post back... we thought we had it last night, just cracked the window and it stopped smoking, but tried to light it up today and started smoking like crazy again.
 
Shannon Freed
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Bought the book suggested by Allan and reading... here is a link to a video to our stove under construction.. (it was filmed by a 12 year old so its not the greatest, but you can def see whats going on)....

http://www.youtube.com/watch?v=KJP6bFv_Zv8

Basic description of our project:

6 inch tube used for J and venting

2 clean outs (have been checked for leaks)

The J tube is constructed and surrounded by a mixture of clay, perlite and refractory cement which forms a rectangular box that the barrel sits on.

I have also posted an album to our organizations facebook page which show all relevant (as far as I am aware) angles of what we have constructed so far.

https://www.facebook.com/media/set/?set=a.636729689676204.1073741825.227754347240409&type=1&uploaded=2

This is a project that will be shared with many on the Pine Ridge Indian Reservation in South Dakota so any help anyone can offer would be greatly appreciated.
 
allen lumley
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Shannon F. : You are giving me the chance to eat my words, posted in a different thread,in a different Forum. Usually people who live in
older houses seem to worry that their house is so 'tight' that if they run their wood stove it will suck all the air out of their rooms. Usually
they want to know if they shouldn't bring in a separate air supply to their wood stoves, this is where I ask them if their stove starts smok-
ing as soon as they turn on the fan over their kitchen range/stove, or the exhaust fan in a bathroom.

Because you are telling me that you have a new cob house, we have to eliminate this possibility, on a still calm day turn off all exhausting
fans, start by having everything ready to build a new fire, open up a window close to your rocket and go through the steps to light your fire
using all small wood. If that works close the window and see if that makes it smoke, then and this will probably be a two person job have a
stove minder watch while you try the exhaust fans one by one, and see if you can recreate the smoking.

This can only be a problem with a very tight house, and is usually not a problem.

In more conventional houses, I find that 50% or more of them have a problem with moisture or even frost trapped in insulation in exterior
walls, I don't recommend a separate air supply for their wood stoves because the furnace will pull back some of that moisture, and sub-
limate the frost and pull that back into the house raising the insulation value of the formally compromised insulation.

In a perfect world your chimney would always be on the lee side of the house, however you may have a problem with varying winds, this
can only be found out by careful observation,and can usually be solved with a homemade storm hood or cap on the existing chimney,
failing that, you may have to raise your stove pipe up to a point well above the peak of the house.

You should also make sure that all the clean out caps are tightly sealed, unfortunately this is only a small start in finding the culprits, but
another way to look at this is, with every small correction you make your stove will start to work better and better !

Peace ! Be safe, keep Warm, PYRO magically - Big Al
 
Shannon Freed
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Big Al: Thank you so much for your reply. The east side is the least wind exposed side of the house as wind usually comes from the north/west however, this is a very windy (in general) part of SD and the wind can often start swirling and coming from all angles. The house is new but still not finished.. It is NOT sealed very tight (yet), most of the leaking comes from the roof (there is a loft covering the entire downstairs except of course where the stairs go up). Most of the windows are sealed but there is at least one that is not and another that is cracked because we have temporary electricity coming from an extension cord from the house next door. As I mentioned, opening one window about an inch helped yesterday (when it was fairly calm) helped but today it didn't.

I thought that the burn chamber was supposed to burn so hot that there wouldnt be much smoke at all... did I misunderstand something in my reading?

Being that it is so windy today and the smoke seems to come and go, I think that your suggestion that the pipe go higher above the peak makes the most sense. (A bit disappointed about this as I had hoped that having a rocket mass heater would negate this need).

Do you think that having double wall pipe on the outside is necessary/would help? (I hope not because that much pipe costs more than $100 )

Looking forward to hearing your thoughts.

Best,

SF
 
allen lumley
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S.F. : Long day here,I'm moving towards bed, I will give your thread a more careful read in the a.m.but don't worry about the chimney's
temperature, we will get it down to around 150 F or lower and it won't be a problem .Be Safe/Warm, PYRO Al
 
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Shanon, things to check:

Barrel gap
connection from the barrel to the pipe
Lengh of the bench pipe

It smokes when the flow is reverted, this is normal, as the burn is not in a high draft insulated tube anymore.

I have problems with wind too, as far as being unusable when there's southern wind. Only solution, raise the tube above the peak of the roof. And may be using a wind vane chimney cap. But as long as you have the tube against your wall, it will never work, when the wind hits the wall, it can't go anywhere, so presure builds up, higher than the presure in the house. Think of a big sail. There's another thing too, your bench might not be dry yet. This slows things down too.

HTH.

Max.
 
allen lumley
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S.F. ; Sent you a P.M., let me know when you get it ! Big Al
 
allen lumley
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Shannon F. this is the 24th, my wife,Martha,andI will be volunteering at a Sustainable living Festival from fri. the 26th, till noon sunday the 28th I
would like to talk with your volunteer, but it sounds like our times will not work out. You're in the mountain time zone right?

Hopefully, you have had the time to read through 'rocket mass heaters' a couple of times. It is too late at this time to expect you to demolish the
start of the horizontal stove pipe, to 'burn off' the galvanizing, though if we have to expose those parts I would recommend that you plan on running
them through a hot fire to get them to out gas, which you will know has happened when the pipe turns from shinny to flat! I am not worried about
the part that will be buried in the cob, but I do strongly recommend that you do dismount the barrel and do a more efficient burn to clean-off
the paint and any remaining gunk in the barrel using the method already talked about!

It is very important that you and ANYONE else who wants to work on your rocket stove, understands the concept of Cross Section Area and is ded-
icated to keeping it whole-y (pun intended). If you can't write it down in your own words so that when someone else reads it,they say 'yes that makes
sense to me ', try writing it down the way it was written ! Then try again !

Starting with a small stone chisel you should be able to create a 6.5'' by 6.5'' square hole about 3'' deeper than than the bottom of your burn tunnel .
The Idea will be to help free the Dragon trapped in your imperfect rocket stove ! We will end up relining this shape into a basic near square shape
6x6, do not worry about the bottom shape just yet.Due to the fact that the stovepipe elbow is made in 4 pieces it is likely that you can catch the edge
of the side closest to to barrel and collapse the elbow, section by section,cleaning it out of the Feed Tube and Burn Tunnel, the 4th and last section of
the elbow can be left in place if the third section pops lose w/out damaging the 4th section. Keep your fingers crossed.

After a simple reline with just clay slip and sand, you can try once again to start a burn in your Rocket Stove starting with a newspaper sheet amount
of shredded paper, to warm up the pipe and create a draw. Just about the way you start any wood stove, But of course, you are stacking your wood
vertically in the Feed Tube, so that the wood as it burns down feeds itself into the fire, with a clean burning fire you soon develop a bed of hot coals
that as they help consume the rest of the wood turns to ash in the lower ash pit, it is important that the transition from the Feed Tube to the Burn
Tunnel be smooth. The floor of the Burn Tunnel back into the bottom of the Feed Tube being level, or slightly downhill to the Feed Tube leaving the
ash pit lower still .

While the barrel is off, being re-burned, you can measure the height of the Heat Riser to figure out the Gap between the Heat Riser and the underside
of the barrel. Look up the right gap in the book ! Hopefully you have had a rocket-y enough burn so that you find a little ash in the bottom of your
Rocket Stove base, this would be a good sign, we also want to see a very clean transition from the bottom of the barrel into the horizontal run and to
the exhaust stovepipe! There is a way to offset the barrel so that less heat is radiated off of the barrel closest to the door and near wall and more out
into the room, this slight change will increase the 'Cross sectional Area' exactly on the side where you transition into the horizontal connection with the
exhaust pipe !

I know you have more than enough information to make a few changes to your Rocket Stove, remember to post your work and the results of some of
these changes. Peace, for the good of the craft, be safe, keep warm, PYROmagicly - Big Al
 
Shannon Freed
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Big Al: Would love for you to chat with my volunteer. He is available during the day on weekdays at my place and most likely during the week in the evenings for another week (at least). If you feel comfortable pm'ing me your phone number and some times we can try to reach you, I can ask him to call you and hopefully set up a time that he and I can call you together. I did send him a link to the book as well. The weather was really bad this weekend so we didnt get to work on it at all but he is feeling very sure that the stove pipe height is the problem because... yesterday (while I was gone) he said that he had it going and working well for about 3 hours straight, then the wind kicked up and he got smoked out. This on top of that we had it going the day before for a few minutes with wind outside with occasional smoke... then we let the fire go out and 20 minutes later a big puff of smoke came out of the burn chamber... a few minutes later another puff came out. It just really seems like the wind is pushing down the pipe..

I did explain to him what you said about cutting out the burn chamber and his analogy was like a tobacco pipe has the extra bit sticking out (which made sense to me), but based on how well it CAN burn... he doesnt think it is key.

Very much appreciate your help/feedback/advice and definitely want to figure this out so that its as good as possible (again since we want to share this with people who really really need it).

Thanks again and looking forward to connecting in realtime if possible.

SF
 
allen lumley
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S.F. : Big AL here ,I'm Available to talk here or P.M.
 
Shannon Freed
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@Big Al or anyone with a clue.... so we raised the height of the exhaust by 6' which gets it over the roof (still not quite to the peak)... when we light it up with newspaper and small sticks it burns great. Even "rickety"... last time we added a bigger piece of wood it started smoking back again...

also, interesting finding... we took of one of the clean out caps and it is slightly moist inside.
 
allen lumley
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Shannon : You still have not sent us a picture of exactly what your Feed Tube and Feed Tube/Burn Tunnel interface looks like, While I believe this could
be a part of your problem, I don't know, and 1 picture is worth a thousand words ! I still worry about sticks stacked vertically in the Feed tube ending
up blocking your Burn Tunnel !

If you can get a clean-smoke free burn on small wood, the very next thing, Is to try 1 medium chunk with several small chunks of wood, there has to
be a flame-front (my word choice) where the individual wood pieces add to the total burn mass without robbing the total of Heat or Oxygen.

Eventually after an hour of more of careful burn any small chunk of wood fed into the feed tube will be ignited by the stored heat radiating out from the
Burn Tunnel! At this point it is only a matter of time and heat absorption and re-radiation till as few as 4-5 chunks of small/medium sized wood will self-
consume in the Feed Tube !

This IS what will happen, when you have removed the last bug, and is the thing that you will soon discover for yourself ! While i am still hoping 'against -
hope that this is as simple as you learning how to feed the Dragon within your Rocket Stove, every effort that you make between now and the point where
you eliminate your last problem is part of your learning curve !
Just today we welcomed three more people into the ranks of 'those that have done' out of the mob of 'those that are trying ' !!

For the good of the Craft, B.s.,k.w., PYRO Logically - Big AL

P. S. Moisture at this point is probably still coming out of the cob, but still you need to use dust devil dry, Tombstone dry , mummy dry, small wood, and don't
be afraid to toast a few sticks extra dry - (while you are watching of course !) A. L.
 
allen lumley
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Shannon ; Check out the Rocket Stove Forum Thread " A Castable burn chamber ", this is what you would have got except for a few unfortunate shortcuts !

For the good of the Craft, b.s.,k.w., PYRO Logically - Big AL
 
Shannon Freed
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@BIG Al: will post a pic tomorrow (do you need me then to take off the barrel?, feeling a bit apprehensive about doing it but will). Looked for the video link you suggested but can't find it. In regards to burning... everything seems to go fine if it is small sticks and newspaper. We cleaned out the burn chamber so there is not any build up of ash... added small more chunk like piece of wood... it burns ok for a few mins then the flame starts to go up the chunk (which is longish) then starts smoking.
 
allen lumley
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Shannon : Mea Culpa; My mistake , type in '' A castable burn chamber'' then click on the link in Thomas Vogel's thread . Big Al
 
Shannon Freed
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BIG AL: I'm confused... first you said to check out a video about burning off the paint on the barrel (which I didnt find) , but these videos are about building the burn chamber and heat riser from scratch and have 8' pipe... mine is already built and has 6"... please advise.
 
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Would you turn that thing down? I'm controlling a mind here! Look ... look at the tiny ad ...
five days of natural building (wofati and cob) and rocket cooktop oct 8-12, 2018
https://permies.com/t/92034/permaculture-projects/days-natural-building-wofati-cob
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